In the Land of the Possible

Samantha Power has the President’s ear. To what end?

Can Power reconcile her ardent human-rights interventionism with the “composite calculus” that must guide American policy?

Photograph by Van Sarki

On July 17, 2013, the Senate Foreign Relations Committee met to consider the nomination of Samantha Power to be America’s Permanent Representative to the United Nations. She was an unusual choice. Although she had been a professor at Harvard’s Kennedy School of Government, and served on the National Security Council as the senior director for multilateral affairs and human rights, she had never been a diplomat. At forty-two, she would be the youngest-ever American Ambassador to the U.N.

Power was best known for her book “ ‘A Problem from Hell’: America and the Age of Genocide.” An indictment of what she called Washington’s “toleration of unspeakable atrocities, often committed in clear view,” it won the Pulitzer Prize in 2003. For her conviction that America has a responsibility to halt or prevent the suffering of civilians abroad, she had been caricatured as the Ivy League Joan of Arc. She had written (in this magazine and elsewhere) with unqualified assurance. As a speaker, “she was a performer of the first order,” Leslie H. Gelb, the former president of the Council on Foreign Relations, told me. “No notes, the fingers and the arms always flashing in the air, and a voice going from a whisper to a shout. She was pure theatre.”

In a 2002 interview on “Conversations with History,” a television series filmed in Berkeley, Power described a hypothetical need for a “mammoth protection force” to police a peace accord between the Israelis and the Palestinians. But after she began working as an adviser on Barack Obama’s Presidential campaign, in 2007, his critics quoted that interview in accusing him of harboring hostility toward Israel, and Power disavowed her comments. In a departure for a journalist, she quietly asked the host of the interview to remove the video from the Web, though portions of it still circulate online. To repair the damage, she subsequently approached Shmuley Boteach, a celebrity rabbi who ran for Congress in New Jersey, Abraham Foxman, of the Anti-Defamation League, and other prominent defenders of Israel, who endorsed her U.N. nomination. She knew that during her confirmation hearing her record, her vision of America’s role in the world, and her transformation from an activist to a political figure would receive intense scrutiny. Tom Nides, a former Deputy Secretary of State, told her that her chance of being confirmed was twenty per cent, at best.

When Power visited Senator Ted Cruz, the Texas Republican, he consulted a page of notes marked with a highlighter. She recalled, “Everything I’d ever written had just been pulled out and reduced, basically, to the things in my search that were the most cringe-worthy, things that you’d just say out of the corner of your mouth in a church basement somewhere, or whatever—they’re not your considered view.”

But Power’s ideas defy the usual partisan distinctions, and she cultivated some unlikely alliances on Capitol Hill. Senator Saxby Chambliss, a Republican from Georgia, where Power spent much of her childhood, shared her belief that, after President Bashar al-Assad of Syria deployed chemical weapons, Obama should have attacked the regime for crossing his “red line.” Chambliss told me, “We had some frank discussions about that. She said, ‘Hey, I’m working for the President—just remember that.’ And I said, ‘Yeah, I know, and here’s what I hope you’ll convey to the President.’ ” Chambliss added, “She has ideas that don’t always coincide with mine from a national-security perspective, but we’re pretty darn close.” He agreed to introduce her at her hearing. (She now sends him notes on his birthday.)

Power, who is five feet nine inches tall, with red hair that reaches the middle of her back, took her seat at the witness table, across from fourteen members of the committee. The gallery was full, and C-Span carried the event live. Power’s relatives and friends in the row behind her included her husband, the Harvard legal scholar Cass Sunstein, and their children: Declan, age four, and Rían, who was thirteen months. Power had resolved to treat the hearing as “you would run a corporation,” she told me; that is, know the objectives, liabilities, and “customer preferences.” The senators, she said, are “trying to get you to make news, potentially, or there can be efforts to create distance between you and the President.” She had to resist both ploys, while bearing in mind the senators’ consciousness of the cameras.

Marco Rubio, the Florida Republican, asked her to explain what she meant, in a 2003 essay in The New Republic, when she called for “a historical reckoning with crimes committed, sponsored or permitted by the United States.” Power disavowed the piece, saying that she “probably very much overstated the case,” and adding, “This country is the greatest country on earth. I would never apologize for America.” Rubio pressed the point, leaning toward the microphone, his eyes sweeping the gallery, and Power had to repeat the line—“This is the greatest country on earth”—two more times.

Ron Johnson, a Wisconsin Republican, brandished notes containing a quote in which Power referred to the United States as the “most important empire in the history of mankind.” He asked, “Do you believe America is an empire?”

Power gave a quick shake of her head and searched for the right words. “I believe that we are a great—a great and strong and powerful country, and the most powerful country in the history of the world,” she said. “Also, the most inspirational.” Empire, she went on, “is probably not a word choice that I would use today, having served.” She added, “Serving in the executive branch is very different than sounding off from an academic perch.”

Rand Paul, of Kentucky, who opposes many forms of American intervention, struck a sober note. He said he was concerned that sending American advisers into the war in Syria would lead to “more soldiers, and then we send platoons and regiments and generals.” He added, “So I would just say that even though noble intentions, I think, are yours, be very wary of what intervention means when we intervene. It’s one thing to send bread, but it’s another thing to send guns.”

Power responded, “Thank you, sir.”

To survive the questioning, Power had set aside the ferocity and independence that made her name. David Rieff, a frequent critic of Power’s humanitarian prescriptions, later derided her performance as that of an “apparatchik whose willingness to pander to her interrogators seemed to know no bounds.” When I asked Power about her performance, she smiled and said, “My thing in confirmation was, I can’t say anything that is not true.” If she received an awkward question, “I need to find something that is responsive, and that may just take it in a slightly different direction, but feels deeply true to me. That was what I felt I was able to do.” On August 1st, the Senate approved her nomination, by a vote of eighty-seven to ten.

In the acknowledgments of “The Audacity of Hope,” published while Obama was in the Senate, he wrote that Samantha Power “combed over each chapter as if it were hers.” At the time, she was a foreign-policy adviser in his office. Eight years later, many aides have left Obama’s Administration, but Power endures, in a role that is roughly equal parts envoy, protector, and, as she puts it, “pain in the ass.”

Shortly after Power was confirmed for the U.N. post, Obama spoke at the General Assembly. Late on the preceding evening, he stopped by Power’s apartment and asked her to look over his speech, and she argued at length for greater emphasis on America’s efforts to promote democracy and human rights. Ben Rhodes, the deputy national-security adviser for strategic communications, recalled, “I’m sitting there thinking, It’s eleven o’clock, it’s twelve o’clock, I have to go do the edits to the speech he has to give tomorrow. There’s no other principal that he would have that give-and-take with, and sit there for an hour and debate how to frame the inclusion of language.”

Eventually, Obama agreed to Power’s suggestions. Rhodes said that Power has consistently urged the Administration to consider intervention, including intervention in the expanding war in Syria. “That doesn’t necessarily mean military force,” he said. “Often, that kind of gets conflated with military action, but I think, as a general matter, she’s favored an activist response to the crises in Syria and Iraq, she’s favored an activist response to the situation in Ukraine, and she’s pushed that envelope in policy development.” In debates about Syria and other matters, she has made strategic use of her ties to the President. Denis McDonough, the White House chief of staff, told me, “There’s been more than one time when I find out that the President has taken a call from Ambassador Power, or has called Ambassador Power late at night when he’s working on a speech, because she has agitated to include a controversial component.”

In the senior ranks of an Administration that is often disparaged as a shrinking corps of fawning courtiers, Power is known for pushing unpopular ideas. “People call her the activist-in-chief,” Madeleine Albright, who served as Secretary of State under Bill Clinton, told me. Jake Sullivan, who headed Hillary Clinton’s policy-planning staff and later served as Vice-President Joe Biden’s national-security adviser, said, “More than other individual actors, Samantha is somebody who will encourage, cajole, push, and prod the whole system: State Department, Treasury Department, Defense Department.” A bureaucrat who is reflexively against the consensus runs the risk of being ignored. But Secretary of State John Kerry told me that Obama does not expect to see everything the way Power does: “I’m confident the President put her there and nominated her because he wanted that.” He went on, “He may not agree with the point of view, and the point of view may not carry the day, but it becomes part of considering what’s out there.”

Because of youth, gender, or disposition, Power has often been underestimated. Gérard Araud, the French Ambassador to Washington, who previously served at the U.N., told me, “I was expecting this sort of N.G.O. girl, considering her past, considering the book she wrote. Actually, she’s a nice mixture of liberal interventionism and Realpolitik.” A senior Administration official said, “It’s easy in some ways to dismiss someone like Samantha Power. Oh, she cares about the marginal, vulnerable, and oppressed! But what she’s managed to do is link the marginal, vulnerable, and oppressed to core national-security interests of the United States.”

Those interests have rarely felt so varied and intractable. Buffeted by a mutating terrorist threat in Syria and Iraq, an Ebola outbreak that attracts intermittent attention in the West, a failed peace initiative in Israel, and Russian aggression in Ukraine, the Administration can point to few satisfying demonstrations of progress. In August, several days after Sunni militants calling themselves the Islamic State, a.k.a. ISIS or ISIL, executed the journalist James Foley, Power had lunch with Elie Wiesel. “He just sat down and he shook his head,” Power recalled. “He said, ‘Samantha, the winds of madness are blowing.’ ”

In the culture of the Administration, where overwork is a status symbol, Power projects harried busyness but not despair. Sunstein told me that, “for someone who wrote a book about genocide, she may have the most mental health of anyone I’ve ever known. She’s deeply non-neurotic.”

Power returns over and over to one question: To what end can America’s power be directed? The President, by his own account, is less sanguine. Last April, he told reporters, during a visit to the Philippines, “There are going to be times where there are disasters and difficulties and challenges all around the world, and not all of those are going to be immediately solvable by us.” For three years, he stayed out of Syria’s civil war, as it produced two hundred thousand deaths and displaced more than nine million people. But by September the Islamic State’s gains in Syria and Iraq had compelled him to launch an American-led bombing campaign that is assailed on one side as halfhearted and on the other as hasty—a combination that has inspired analogies to Lyndon Johnson’s reluctant escalation of the war in Vietnam.

The President’s ambivalence about America’s ability to shape events puts Power in a predicament. In 2012, she launched a White House task force called the Atrocities Prevention Board, which was intended to insure that U.S. government agencies focus on emerging human-rights crises before they reach the level of genocide. Human-rights groups applauded its founding, but, in an assessment a year later, the Center for American Progress, a Democratic think tank, concluded that “the continuing tragedy in Syria has cast a pall over the board’s work and has led many to sharply question its overall efficacy.” A former senior White House aide said, “Are people like her around to give credibility, though they’re actually not listened to? I think that’s a fair question, and I don’t know what the answer is.”

The contrast between Power’s ardor as an activist and her duties as an adviser has exposed her to the criticism that her commitment to the Administration, and to her own advancement, comes at the expense of her principles and her reputation.

Kirk W. Johnson, the founder of the List Project, which advocates for the resettlement of Iraqis who worked with Americans, read “ ‘A Problem from Hell’ ” when he was an undergraduate: “I was one of the first people in the room when she came to the University of Chicago to give her book talk.” After working for U.S.A.I.D. in Iraq, Johnson, and other advocates, met with Power at the White House, because she was the point person on Iraqis who had worked with Americans. Programs that resettled thousands of such Iraqis have recently been shut down or suspended, despite tens of thousands of pending applications; the Administration says that moving too fast could risk admitting a terrorist. Johnson says that Power told him and others, “Having been in your shoes for most of my career, I know how frustrating that is to hear.” But Johnson believes that she endorsed the security argument too credulously, and faults her for not achieving more results. “The reason that people like us are so animated about Samantha is that if she disappears into this system, if she gets ground up in Washington, with that knowledge of the history of bad policy, that’s a really dispiriting thought.”

David Rothkopf, the editor of Foreign Policy, whose latest book is “National Insecurity,” told me, “Here is the person who wrote the best-reported, analyzed cri de coeur on genocide, in an Administration that has effectively said, in the face of humanitarian disasters, We’re going to do very little, whether it is the continuing catastrophe in the Democratic Republic of Congo or Syria or the brewing problem with Rohingya”—Muslims persecuted in Burma. “We will periodically do something, like send in helicopters to look for two hundred missing schoolgirls, or blow up somebody on the Horn of Africa. But this has not been the antidote to Rwanda that she may have wanted.” As for Power’s influence on other Administration officials, he said, “Whereas she could be the North Star to some extent, she actually ends up being a kind of counterpoint, illustrating the fact that they are not, for the most part, living up to their convictions.”

The culture of the United Nations is deferential, noncommittal, and risk-averse. A Secretary-General in the eighties, Javier Pérez de Cuéllar, was said to be so mild that he could fall out of a boat and not make a splash. When Power arrived, it wasn’t clear how she would approach that environment. “Seldom have I seen a colleague with such an appropriate last name,” Karel van Oosterom, the Dutch Ambassador, told me. “In Dutch, we have a strange expression, ‘She doesn’t speak with flour in her mouth.’ She can be very clear, and she can also maintain perspective.”

Within weeks of her arrival, she was thrust into negotiations over the disposal of Syria’s chemical weapons. Her predecessor, Susan Rice, had become Obama’s national-security adviser, and, for Power to succeed, she would need Rice’s support. She and Rice had first encountered each other years earlier, under uncomfortable circumstances: in Power’s book on genocide, she quoted Rice, as a young aide in the Clinton Administration, asking colleagues in regard to Rwanda, “If we use the word ‘genocide’ and are seen as doing nothing, what will be the effect on the November election?” An aide who worked in the 2008 Obama campaign told me that, during a private session to prepare Rice for Senate confirmation, she was asked about the quote in Power’s book. But she and Power became friends and allies; Rice visited her in the hospital each time Power had a baby. Once Power was in New York, she called Rice frequently to test her ideas and to stay aligned with the White House.

She had an easier time attending to the needs of her new colleagues. Other ambassadors had found Rice harsh and often unwilling to listen. Power sent drafts for comments and shuffled her schedule to accommodate colleagues. She opened a Twitter account and posted many times a day, in a voice ranging from earnest (“Ethiopia’s progress must extend to civil rights”) to glib. When Russia denied that its combat units were in Ukraine, she wrote, “Might have gotten away with this before invention of cameras.” She writes some of the posts, and her staff drafts others, which she edits. She has attracted more than a hundred thousand followers, and her tweets feed the criticism that the Obama Administration favors “hashtag diplomacy.”

It’s impossible to talk about Power without noting that she looks like nobody else in the Cabinet, or anybody who has ever been in the Cabinet: the height, the hair, the booming voice. At a cocktail party where a photographer was taking pictures of guests in pairs, a U.N. veteran slinked away, whispering to me, “I don’t like to be photographed with her alone, because I look like a midget.” She played basketball and ran cross-country in high school; now she plays squash with Sunstein. She stalks down a hall, head bowed, with such pace and purpose that I once watched her entourage almost follow her into the ladies’ room. Araud, the French Ambassador, who became one of Power’s closest collaborators, told me, “As a Frenchman, I’m not condemned to be politically correct, and one day we were on the Security Council, and I sent her an SMS saying, ‘On behalf of the French delegation, I want to tell you, you are very beautiful.’ ” (Power replied, “This is one of the nicest SMSs I have ever received.”) Araud added, “I think she likes me because she knows how to manage me. Really, she has seduced me.”

Power is sensitive about appearing unduly ambitious. “My career is not well thought out,” she told me, repeating the idea in several conversations. “Every choice has been instinctive and, quite literally, impulsive in many ways.” And yet, for nearly two decades, Power has left others with a clear sense of her long-range aspirations for higher office and her muscular style of foreign policy. She began her career as a reporter in Bosnia, where her colleagues joked that she might become Secretary of State and reignite the Cold War.

As Power has risen, she has acquired an eclectic range of contacts. “I don’t know if I will help her more by praising her or attacking her,” Henry Kissinger told me. He had classified her as “one of the liberals who know their emotions better than their analysis,” but, after a series of meals and a Yankees game, he has a different view. “She has an excellent analytical mind, and even on matters where I might have come to different conclusions I respected her analysis. Second, she knew the difference between being a professor and being a policymaker, so, when she analyzed contemporary problems, she and I didn’t differ all that much.”

Power has a way of manipulating the targets of her lobbying without alienating them. On the question of resettling Iraqis, for which she had attracted criticism, Power raised the issue with Nides, at the State Department. “I’m a liberal Jew, and she realized she could play into my anxiety” about unprotected refugees, he said, laughing. Nides started arguing, at meetings, to speed up resettlement. “I’m pounding the table, and I’m thinking, What am I doing?” He said, “Part of it was that I didn’t want to disappoint Samantha.”

Since 1947, the official residence of the U.S. Ambassador to the United Nations has been a penthouse at the Waldorf-Astoria—high ceilings, burgundy walls, art works by Hopper, Christo, Rauschenberg, Johns, and others. (In October, a Chinese insurance company bought the Waldorf, for two billion dollars; the U.S. has not decided whether it will leave.) Power’s office is on the twenty-first floor of the U.S. Mission, on First Avenue, with a sweeping view of the East River and, in the foreground, the blue-glass U.N. Secretariat Building. On her shelves, she has a basketball given to her by Obama (inscribed “You will always be my MVP”); a program from the memorial service for her mentor Richard Holbrooke, whom she met in Bosnia, where he was a U.S. envoy negotiating for peace; and a photograph of her son, Declan, with his head in a bowl of apples on the coffee table in the Oval Office.

In a gesture intended to convey humility, Power is trying to meet each of the U.N.’s hundred and ninety-three permanent representatives at their offices, instead of hers. (By her count, as of December, she had visited a hundred.) Three weeks after she was sworn in, she visited the two-room mission of the Central African Republic, one of the poorest countries in Africa. Six months earlier, Muslim rebels had mounted a brutal coup, and anti-Muslim gangs retaliated with wanton bloodshed. The American government, which had closed its embassy the previous year, had little knowledge of the events. In an encounter with a senior American diplomat, a French official raised the subject of the country, known as C.A.R., but the American thought he was talking about D.R.C.—the Democratic Republic of Congo. Power spoke with Ambassador Charles Armel Doubane, who described mobs pulling men and women from buses and killing them on the basis of their religious and ethnic identity. “It just sounded so much like Bosnia and Rwanda before the genocides,” she said. “The sirens went off.”

She asked her staff to present possible responses. Power decided to visit C.A.R.; it would be the first time a U.S. Cabinet official had done so since the country was founded, in 1960. In December, shortly after sixteen hundred French soldiers arrived in the capital, Bangui, Power flew in with staff members and reporters. During the trip, she announced that the United States would provide a hundred million dollars in support of French and African Union troops.

Human Rights Watch had been documenting the carnage but had struggled to generate government action. Ken Roth, the executive director, told me that Power cannily leveraged her office to that end. “It was an area with no real strategic value, no national interests, subject to utter neglect and indifference in Washington. She was able to step in and alert people to the potential of genocide and then overcome a stingy reluctance to pony up for a peacekeeping force.” He went on, “While the Central African Republic remains extremely precarious, it could have been a whole lot worse.”

The crises of this moment—Ebola, ISIS, Ukraine—demand the fragile assemblages that bureaucrats call “multilateral” solutions. In September, I spent a few days following Power in the throes of “high-level week” at the General Assembly, when heads of state sweep in to speak, if not always to act, in a spirit of collaboration. On Tuesday, September 23rd, the United States and its allies bombed Syria for the first time, seeking to destroy ISIS’s rear base of operations. In an editorial, the Times called it “a bad decision,” because the Administration had failed to explain “how this bombing campaign will degrade the extremist groups without unleashing unforeseen consequences.” In New York, Frank Rich wrote that the absence of an exit strategy made the intervention “the very definition of a quagmire.”

President Obama, in his speech before the General Assembly the next day, offered his rationale for the bombing campaign. He described the air strikes with a moral, if not a strategic, certainty that he had previously resisted: “There can be no reasoning, no negotiation, with this brand of evil. The only language understood by killers like this is the language of force. So the United States of America will work with a broad coalition to dismantle this network of death.” It fell to Kerry, Rice, Power, and others to try to recruit and maintain that coalition.

The next afternoon, following a meeting with Obama and Egypt’s President, Abdel Fattah el-Sisi, Power slumped into the seat of an armored black Suburban as it wound its way through traffic from the Waldorf-Astoria to the U.N. She said that she thought people underestimated the complexities of deciding “whether to join an ISIL coalition, or whether to get involved in a meaningful way with Ebola.” She went on, “You’re thinking, Well, as soon as I join this coalition in a prominent way, then my nationals are vulnerable to ISIL, or my citizens may contract Ebola.” Her message had to be clear: “We are not accepting that countries just get to sit back and let the United States meet threats that are going to roost in their worlds just as easily as they are in ours.”

A few hours after the President’s speech, Power ushered Obama into the Security Council chamber for an unusual session. Washington wanted to obstruct the flow of foreign terrorists into Iraq and Syria. The U.S. estimates their numbers at more than a hundred Americans and at least twenty-seven hundred Europeans. The small chamber, no larger than a college lecture hall, quickly filled with potentates and heads of state. It had the feel of an impersonators’ convention: there was Goodluck Jonathan, of Nigeria, in his signature black fedora; Paul Kagame, of Rwanda, thin as a reed; David Cameron, tall, with broad, pale cheeks and wearing a trim dark suit. And on they came. Erdoğan of Turkey, Abbott of Australia, and, finally, the Americans: John Kerry, Susan Rice, and Obama, accompanied by Power, who wore red stilettos that put her well over six feet.

A few minutes before the session began, Obama received news that extremists in Algeria had beheaded, on camera, a French hostage, Hervé Gourdel. Opening the meeting, Obama nodded to François Hollande, the French President. “If there was ever a challenge in our interconnected world that cannot be met by one nation alone, it is this,” he said. After four hours of discussion, the Security Council passed a resolution compelling nations to enact laws against travelling to join terrorist groups or paying for others to do so. Russia and China joined it, causing some human-rights advocates to worry that countries might try to use the provision as an excuse to lock up political opponents.

Now Power and the others had to prevail on countries to follow through. Power told me, “It wasn’t just like a bumper sticker—‘Foreign terrorist fighters are bad.’ There’s a whole series of obligations.” She arranged to take foreign ambassadors to the 9/11 Memorial Museum, instead of on the more customary excursions to see the Mets or the Knicks. (“The Samantha Power Prozac package,” she joked.) She wanted to remind her peers of the human implications of terrorism. “It’s not a geopolitical strategic abstraction,” she said. “It is about groups that target families who are flying on airplanes, and take the lives of firefighters who are trying to rescue other people. It’s about preventing that.” So far, progress had been slow. “People have not shut their borders, they have not put laws in place, they have not acted with the urgency that is needed.”

Power often talks about “bending the curve,” her preferred phrase (and Obama’s) for a good intervention—the point where the technical meets the humane. She is from a family of doctors. The surname comes from the Irish “de Paor,” meaning “of the poor.” Her mother, Vera Delaney, was an Irish field-hockey standout and a squash champion, who was fascinated by medicine. “On the sports field, when her knees were bloody, she would want to watch as they stitched up,” Power said. Delaney persisted, even though women were discouraged from studying medicine, and became a nephrologist.

She married a Dublin piano player, raconteur, dentist, and drinker named Jim Power—“a fearsomely formidable pub debater,” as the Irish Independent once put it. “I was extremely close to my father, inseparable,” Power said. “Where we hung out most of the time was the pub.” Her father expounded on the day’s papers, while she read mysteries by the light of a slot machine in the basement. Her parents’ marriage didn’t last. “My mother, in effect, started leading her own life,” Power said. At the hospital, Delaney fell in love with her boss, Edmund Bourke. Divorce was illegal in Ireland, and they wanted more opportunities in medicine, so, when Samantha was nine and her brother was five, the family moved to Pittsburgh and, later, Atlanta. Jim Power remained in Ireland. She said, “We stayed in touch, and, then, the drink, I think.” She trailed off. He died when she was fourteen. Sunstein recalled that, decades later, on a trip to Ireland, Power took him to visit her father’s favorite pub, where they met a woman who had worked behind the bar and remembered her dad. Others seemed to drink just as much, and Power asked, “Why do you think my dad was the one who died?” The barwoman answered simply, “It’s because you left.” Power told me, “I knew he was drinking too much. But I had no idea he was sick—he was just forty-seven, and his death was devastating.”

Power became American through baseball. She went to Yale and, as an undergraduate, wanted to be “the next Bob Costas.” (When she worked at Harvard, her screen saver was a Sports Illustrated cover of a shirtless Nomar Garciaparra, the Red Sox shortstop.) In June, 1989, after her freshman year, she was interning at CBS in Atlanta when she saw a live feed from Beijing: tanks and soldiers were ending the democracy protests in Tiananmen Square. She later told the television interviewer Harry Kreisler, “It was the most shocking thing I’d ever seen,” and added, “I thought, Oh, God, what am I doing with my life?” She turned to history and writing, and after graduation, in 1992, as the war expanded in Bosnia, she interned at the Carnegie Endowment for International Peace, accompanying its president, former Assistant Secretary of State Morton Abramowitz, to events. He was “incurably constructive,” she said. “There was just nothing he encountered where his mind didn’t go to, What can you do?”

She wanted to report from Bosnia, but she had no experience and news organizations wouldn’t back her application for a U.N. credential to cross the border. Carnegie shared a building with Foreign Policy, and when the editor left one night she sneaked into his office and stole some stationery. “I wrote this letter saying, ‘Please provide Samantha Power with all the credentials she needs.’ ” It worked.

In late 1993, she moved to Zagreb, and then Sarajevo. She started learning Serbo-Croatian and wrote for the Boston Globe, the Washington Post, TheEconomist. Laura Pitter, who was stringing for Time, said, “There were snipers picking off women and children. I think we all believed that if we explained to the rest of the world what was happening the world would do something about it. But, with every report, the world kept drawing the bottom line lower and lower.” Barbara Demick, at the time a correspondent in Sarajevo for the Philadelphia Inquirer, recalled, “Samantha was a breath of fresh outrage.” She went on, “I remember going into a meeting with Michael Rose, who was the U.N. commander at the time, and he said, ‘Here comes the Bomb the Bastards Bunch.’ ” That became their nickname.

In 1995, the same year Power enrolled at Harvard Law School, NATO bombed Serb forces, and she rejoiced. She told me, “These guys who had been terrorizing these people were going to be stopped!” Until then, she had been dismayed that nothing she and her colleagues wrote about—Srebrenica, rape camps, torture—seemed to have much effect. “Then, suddenly, not only do we care but we’re prepared to put something very meaningful and difficult on the line!” She added, “Your average journalists knew that they should not admit that was their longing. But you see that much terrorization of people and you’re just a human being in that context, and people were rooting for that outcome and that intervention.”

In her second year of law school, Power took a class on the just use of force. “I began looking at the historical cases of genocide, looking at the Armenians, the Khmer Rouge, and Saddam Hussein’s Al Anfal campaign and Rwanda,” she said. She wrote a paper for class and sent it to Anthony Lewis, then a Times columnist, and Martin Peretz, who was editing The New Republic, both of whom followed the Bosnia war closely. They told her she should try to turn it into a book. She did, and the result was “ ‘A Problem from Hell,’ ” published in 2002. In it, Power reconstructs deliberations in the Clinton White House and in the State Department and other agencies as officials overlooked or rejected proposals for U.S. intervention. She criticized those who avoided using the word “genocide” in their statements, and praised those who resigned in protest of inaction, such as Marshall Harris, a thirty-two-year-old Bosnia desk officer at the State Department. America’s repeated refusals to end genocides were not “accidental products of neglect,” Power wrote. “They were concrete choices made by this country’s most influential decision-makers after unspoken and explicit weighing of costs and benefits.”

After Power’s book won the Pulitzer, she toured American college campuses, drawing large crowds. Time chose her as one of its 100 Most Influential People. In 2004, on assignment for The New Yorker, she detailed the ethnic cleansing of non-Arabs in the Darfur region of Sudan, where a hundred and twenty thousand people had lost their lives. In her writing on atrocities, Power often talked of a “toolbox” of interventions—sanctions, asset freezes, prosecutions in the International Criminal Court, and, in certain circumstances, military force—but, most of all, she called for a moral commitment to respond. On the tenth anniversary of the Rwandan genocide, she appeared on “Charlie Rose” and said that the history of inaction held lessons for the U.N. and other organizations. “They can’t live by the maxim that they do in Washington, which is that if you make a moral argument you’re not going to get invited to the next meeting. Make the moral argument and see. Leak the fax that warns of the extermination of a thousand. Leak it, and see whether the member states actually can be shamed into acting. Don’t check the weather. Don’t live in the land of the possible. Push.”

In early 2005, Power received a dinner invitation from Obama’s Senate office. He had read her book and wanted to meet her. He showed up late and was clearly preoccupied. “He was reaching out to tons of people, I think,” she said, but he was the only senator who had ever got in touch with her about her writings.

She sensed that his interest in the book focussed on the reasons that the government did not live up to its ideals: “Why do we think this about ourselves and yet do this? What are the domestic political dynamics that shape it, where do these decisions get made? He was interested in systems and outcomes and misalignment in the two.” She concluded that he had less interest in ideology than in results: “People say, ‘Is he a realist? Is he an idealist?’ He’s very interested in the protection of the American people, first and foremost, our values, our national security, and our economic interests. What he is most interested in is whether the particular policy tool is likely to produce the outcome that anybody is claiming it is going to produce.”

By the end of the dinner, she had proposed taking a leave from Harvard to work in Obama’s office. At the time, she was researching her next book, “Chasing the Flame,” a biography of Sergio Vieira de Mello, a rakish Brazilian diplomat who headed the U.N. mission to Iraq and was killed in a bombing in 2003. Gary Bass, a friend of Power’s who teaches at Princeton, told me that, although she still had high confidence in America’s ability to shape events, the Iraq War had tempered that faith. “It’s a humbling and humbled book,” he said. Vieira de Mello was trapped in the rubble while U.S. soldiers, who had been sent to the scene without proper equipment, struggled to save him. Power wrote, “The most powerful military in the history of mankind was forced to rely for rescue on brute force, a curtain rope, and a woman’s handbag.”

In January, 2008, while campaigning for Obama in Iowa, Power started dating Sunstein. He and Obama had been friends since their days teaching at the University of Chicago. Sunstein, who was serving as an informal legal adviser to the campaign, was ranked as the most frequently cited legal scholar in America. “He had written so much that I thought he was probably as old as Oliver Wendell Holmes,” Power said. (He is sixteen years older than Power; he was divorced and had split up with his companion of more than a decade, the University of Chicago professor Martha Nussbaum.) On an early date, Power answered a call from Holbrooke, who asked to speak to Sunstein. Holbrooke greeted him cheerfully and said, on behalf of himself and Abramowitz, “If you hurt her, Mort and I will break your kneecaps.”

Power and Sunstein married on July 4th, in County Kerry, in a boisterous three-day affair. At one point, boat captains urged Power to cancel a scheduled ride because of rough seas; Power went ahead, and regretted subjecting her guests to it. “Several puked over the side,” she said. In a toast, the commentator Jeff Greenfield hailed the wedding as “a cross between ‘The Poseidon Adventure’ and the Bataan death march.”

By then, Power’s role in the campaign was over. In early March, as Hillary Clinton struggled to halt Obama’s surge in the primaries, her campaign attacked his integrity from a variety of angles; a Clinton aide called it “the kitchen sink” strategy. Before the primary in Ohio, where many voters blamed the North American Free Trade Agreement for an exodus of jobs, the Clinton campaign accused Obama of dishonesty. Canadian officials had said that his economic adviser Austan Goolsbee told them privately that Obama’s protectionist talk was only “political maneuvering.”

Days later, while on a book tour in Europe, Power was giving an interview to the Scotsman when she received a call from Goolsbee, who told her that the Clinton campaign was taking out ads attacking him. After the call, she turned back to the reporter. “I just vented as you would to someone you know—which was idiotic, amateurish,” she told me. The reporter quoted her saying of Clinton’s tactics, “She is a monster, too—that is off the record—she is stooping to anything.” Given her experience as a journalist, Power’s account seemed like spin. But she stuck with it: “This is completely my doing, and I said horrible things that weren’t my view before and haven’t been my view since. But in the heat of being really pissed off about something that her campaign had done I kind of let loose on her.”

As the story spread, she called Holbrooke, from Ireland, and asked if he thought it would go away. “He flipped through the channels and he said, ‘Well, you’re leading the “Today” show—that’s not a good sign.’ ” Power stepped down from the campaign the next day. (Sunstein had flown in for a planned visit, with an engagement ring in his pocket, but the timing didn’t seem right; he postponed the proposal.)

That summer, Holbrooke, who was close to Clinton, brokered a meeting at Clinton’s Manhattan office, as Power’s “wedding present.” (When Power told Obama about it, he reportedly said, “Gee, most people get toasters.”) Clinton became Secretary of State, and she and Power worked together on Libya, land-mine policy, women’s empowerment, and other issues. In 2011, Power travelled with Clinton to Europe. A member of the delegation, who described the mood between the two women as frosty, recalled, “I went into the cabin in the plane, and everyone was civil, and I remember Samantha being anxious, trying to make it work.” Recently, a former senior official who is close to Clinton told me, “There’s no sense of strain or problem between them. But I wouldn’t describe them as particularly close.”

Today, more than six years after a word nearly cost her a career in government, Power exhibits a kind of post-gaffe stress disorder. Fiery and profane in private, she tends to be mind-numbingly dull on the record. When I asked her a benign question about what she’d learned working for the Administration, she said, half-jokingly, that she had no concise answer “other than ‘Don’t trust the press.’ ” If she doesn’t like a question, she squints, pauses, and then parses it into as gentle a query as possible. When she appeared on “The Daily Show” last month, Jon Stewart set her up to make an easy crack about Congress. She replied, “We are hopeful that we will see Congress act in support of the effort we are undertaking,” leading him to remark, “That was super diplomacy. That was Ambassadorific.”

The presidency of the U.N. Security Council is a rotating position, allowing the representative of each member country one month to shape the agenda. Power’s rotation in September coincided with a growing recognition of the threat posed by the Ebola virus. Speaking by video from Liberia, Jackson Niamah, a doctor with Médecins Sans Frontières, told members of the Security Council that people “are sitting at the gates of our centers, literally begging for their lives,” and “dying at our front door,” because the clinic lacked the beds to hold them. “If the international community does not stand up,” Niamah said, his voice rising, “we will be wiped out.” In some areas, the number of cases was doubling every three weeks.

Ban Ki-moon, the Secretary-General, asked for a billion dollars in aid, but after a month barely a third of that money had arrived. Only twenty-five countries had offered more than a million dollars. Aid workers estimated that they needed a thousand vehicles; they had sixty-nine. They were short of helicopters, protective suits, and other equipment. As the virus spread, and people abandoned schools and farms, the risk of famine grew. Ordinary medical care was collapsing, setting back years of recovery from war and unrest in West Africa. “This is mad,” Power told an audience of Irish and Irish-Americans in New York, comparing the crisis to the potato famine. In America, anxiety and misinformation were spreading. A Reuters poll found that nearly three-quarters of Americans favored a ban on flights from the worst-affected countries. In Maple Shade Township, New Jersey, parents of two students from Rwanda agreed to keep their children home from school, even though Rwanda had no cases of the disease and is nearly three thousand miles from the center of the outbreak.

Power decided to visit West Africa, to tamp down fears in America and to draw attention to the inadequate supplies. On October 23rd, two days before she was to depart, Craig Spencer, an American doctor who had been treating patients in Guinea, tested positive for the virus after returning to New York City. The next day, Andrew Cuomo and Chris Christie, the governors of New York and New Jersey, imposed a mandatory quarantine on anyone arriving from West Africa who had been in contact with Ebola patients, even if the traveller had no symptoms. Aid groups protested that this would stigmatize returnees, sow fear, and cripple the effort to recruit doctors and nurses.

Power stayed up the night before the trip, ambivalent about whether to go. If she was quarantined upon return, the sight of a Cabinet officer in isolation could heighten the panic. But the risk of a quarantine seemed low, and the press coverage of the trip could challenge the notion that the U.S. should protect itself from Ebola by blocking flights and rejecting visitors. Infectious diseases, she said, are “the paradigmatic cases of why our interests are entwined with those of others.”

On October 25th, she boarded an Air Force Boeing 737 with a security staff, a team of aides pecking at BlackBerrys, and a doctor who was monitoring the group for signs of infection. She visited five countries in four days, determined to generate as many headlines as possible. I joined the trip, along with reporters from Reuters and NBC, and we received a packet of instructions for preventing infection, including no shaking of hands. (“You may place your hand over your heart, you may bow, or you may offer your elbow if a clothed one is offered.”) Andrea Mitchell, of NBC News, asked, on Twitter, if Cuomo would have Power “return to U.N. or quarantine?”

The plane touched down at dawn in Conakry, the capital of Guinea, the initial site of the outbreak. A convoy of armored S.U.V.s carried us through narrow rutted streets, flanked by shanties and open sewers. The city’s Ebola treatment center was a hospital with black mold reaching up the yellowed walls. One of Power’s colleagues, Jeremy Konyndyk, a tall, phlegmatic thirty-seven-year-old former aid worker who runs U.S.A.I.D.’s office of foreign-disaster assistance, described Guinea’s epidemic as being “at a managed point, but right at the edge of potentially getting into unmanageable.”

At the National Operations Center for the Ebola response, Power attended a meeting in a small room with two naked fluorescent bulbs and a Guinean flag taped to the wall. Midway through the meeting, the air-conditioning conked out. Then the lights shut off. The Guinean hosts kept talking, and, after a few moments, the electricity blinked back on. Everywhere Power went, she heard that local health centers did not have bleach. There were too many calls to the local emergency number, so, often, nobody answered. The bureaucracy was so unprepared for the crisis that when a local government needed to change the tires on an ambulance it had to request approval from the capital and wait for a reply.

At the city’s main mosque, she shared a couch with three young people who had recovered from the disease. She asked if they wanted to say anything, and a small, slight woman, in a bright floral head scarf, spoke up. Her name was Fanta Oulen Camara. The virus had killed six members of her family. She had been a philosophy teacher before she got sick; she recovered in April, but the school would not let her return, fearing that she would scare away students. Power turned to Camara and said, “Can I have a hug?” Camara hesitated, then she held out a fist. “All right, fist bumps for everyone,” Power said.

In Freetown, the capital of Sierra Leone, the front page of Awareness Times, a daily newspaper, carried a triple-decker headline: “OVER 700 PEOPLE BURIED IN RURAL FREETOWN AREAs.” A chart noted, “Total Laboratory-Confirmed Cases: 3,562.” At every building, Power waited for the NBC camera to get in position and then washed her hands in water and bleach, and someone held an electronic thermometer to her head. A dilapidated stadium had been converted into a training center for health workers. As a former British colony, Sierra Leone was receiving aid from the United Kingdom. Two British soldiers in green-and-tan camouflage were teaching a roomful of young Sierra Leonians how to properly put on protective suits, goggles, and face shields. A student in a dress and heels, with her purse on her lap, studied the soldier sealed up in his white Tyvek suit and raised her hand. “What if you want to scratch your eye?” she asked.

“Resist the urge,” the trainer said. “It’s not worth it.”

The desire to see the Ebola crisis close up, combined with the need to maintain enough distance to avoid a political debacle, created some awkwardness. Once, a member of the delegation pointed at a crowd and said, “Looks like a party.” A reporter perked up and asked, excitedly, “A body?” The moment passed.

The United States had pledged to send four thousand troops to build seventeen Ebola treatment units in Liberia, where a civil war had killed a quarter of a million people. We flew by helicopter to Bong County, a rural region a hundred and twenty miles east of the capital, Monrovia. The U.S. Navy had set up a mobile testing lab—everything needed to test patients for Ebola, in twenty-seven boxes. Benjamin Espinosa, the operations-department head in the Navy’s Biological Defense Research Directorate, walked Power through a process that had cut the testing time from four or five days to as little as two and a half hours.

Down the road, her S.U.V. reached a sign, “Leper Colony, Suakoko District,” and turned onto a dirt road through the forest, arriving, after half a mile, at an open-air Ebola hospital run by the International Medical Corps. It was a cluster of makeshift buildings with metal roofs, blue nylon walls, and orange plastic netting that marked areas where patients and doctors were permitted. Sterilized rubber boots were drying upside down on wooden posts, resembling a field of black plants. Hospital staffers had prepared a tour. But one of Power’s aides said, “This is the farthest we’re going to go.” Another said nervously, “There is a D.C. dynamic.” If Power went inside, she might get quarantined in New York. She peered across a patch of gravel, and two boys—Solomon, in a white T-shirt, and Joe, in a black T-shirt—peered back.

Joe waved, and Power returned the wave.

“How old is he?” she asked.

Pranav Shetty, an emergency-room doctor from Pennsylvania, who ran the Ebola hospital, said, “The younger one is eleven, and the older one, I think, is fourteen.”

“What is the survivability here so far?” Power asked.

“Of the confirmed cases, about forty per cent survive.”

The younger boy had come in with a sibling, also sick. They shared a room. The sibling died.

“Parents?” Power asked.

“At least one died, and one may have left,” Shetty said. “Sometimes it’s unclear.” Out of a family of twenty people, twelve had died.

In the six weeks since the hospital opened, it had saved twenty patients. Thirty had died, and fourteen were in treatment. None of the staff had become infected, but doctors and nurses in America were cancelling their plans to come. Sean Casey, the country director for the International Medical Corps, said that three had dropped out the previous week. “We have some staff who are here who want to leave early now.” The hospital was hoping to have a staff of sixty foreign medical personnel, and the largest supply usually came from America. “I’m not sure that we’re going to be able to get there,” Casey said.

One evening, after the day’s last tour, I met Power in the bar at the hotel. She sipped a whiskey and carried one of the green bound notebooks favored by federal workers. Since she joined the government, her vocabulary has tilted toward techno-jargon; in her notes, she referred to obstacles as “rate-limiters” and “gating issues.” In a conversation, she described a head of state’s stubbornness as a “characterological direction of error.” But she retains a reporter’s instinct for amassing facts and deploying them to extract more. That morning, she had heard that the rate of safe burial in one area had reached nearly a hundred per cent; by the afternoon, she was using that fact in a speech as an argument against despair. “People in the field often have these thoughts, but they just get filtered as you go up,” she said. She relished being out of the office again. “It’s oxygen for me,” she said. “I’m like a plant.”

Power’s muted entry into the Obama Administration—on the National Security Council—in January, 2009, entailed long hours and limited influence. It afforded her less access to Obama than she was used to, and some colleagues doubted that she could adjust to a low-profile role. “She did not have a big enough job to throw her weight around, but people knew she was Obama’s friend, so they couldn’t mess with her. She was an upstairs and downstairs person, and there are very few others like that,” her friend Kati Marton, an author and Holbrooke’s widow, told me. Sunstein had been hired, too; he headed the White House Office of Information and Regulatory Affairs. Nicknamed the government’s “regulatory czar,” he attracted obsessive attention from Glenn Beck, who called Sunstein and Power “the most dangerous couple in America.” Sunstein received death threats.

Initially, Power tended to drone on at meetings, and she had yet to learn how to “wire” a room, by planting and testing her ideas with others beforehand. “You almost watched her learn these skills,” Harold Hongju Koh, the State Department’s top lawyer at the time, said. “She became crisper and sharper and she would work the room.” When Obama won the Nobel Peace Prize that October, she worked on several drafts of his speech, which emphasized the justified use of force, arguing that a President can never be Mahatma Gandhi or Martin Luther King, Jr. In her office, Power hung a copy of the text, scrawled with Obama’s handwritten notes. Gradually, she established a voice. Ben Rhodes, the deputy national-security adviser, said that, in the Oval Office, Obama began asking, “What does Samantha think about this?” Rhodes said, “Even when she’s not there, he’ll want to know. You can kind of hear her voice.”

Unlike Defense Secretary Robert Gates, Vice-President Joe Biden, and others who had risen through the foreign-policy establishment, Power favored aligning the United States with citizen-led movements, instead of with leaders. That divide became clearest in March, 2011, when American spy satellites showed Muammar Qaddafi’s military moving toward Benghazi, the eastern stronghold of Libya’s opposition forces. On radio and television, Qaddafi said, “There will be no mercy.” He promised to hunt the rebels down “alley by alley, house by house, room by room.”

Power was “the first and most decisive advocate for aggressive actions in Libya, and she was a consistent voice before anybody else was,” a senior official involved in the Libya actions told me. “She really put on the agenda the use of military power to respond to what was happening there, at a time when the President wasn’t sure.” Dennis Ross, then Obama’s top Middle East expert, said, “She never minded being the odd one out. She would argue her position regardless of what the lineup was.” On Libya, he said, “she would keep coming back, even though it wasn’t being particularly well received.”

With the backing of the Security Council, the U.S. and its allies imposed a no-fly zone and bombed Libyan forces. But Gates opposed using the U.S. military to prevent a humanitarian disaster unless there was a clear image of what would follow. In his recent memoir, “Duty,” he recalls telling aides to withhold information on military options from staff members at the National Security Council and the White House: “They don’t understand it, and ‘experts’ like Samantha Power will decide when we should move militarily.” When I asked Gates about that criticism, he said, “It was not just her. It was several White House staffers. They were Ben Rhodes and Samantha and, I might add, Susan Rice—particularly strong advocates of getting involved in a U.S. military engagement. And I don’t know whether these folks have a guilt complex over the Clinton Administration’s having botched Rwanda, where the U.S. did nothing, or what, but they are very much driven.” He said, “It becomes detached from U.S. national interests. So I was totally opposed.”

The image of Power, Clinton, and Rice became a cartoon—Obama’s Valkyries leading him to war—but Gates does not believe that Obama ever broadly embraced Power’s expansive view of humanitarian intervention. He said, “I think he was being pressured by the Europeans, particularly the French and the British and the Italians, and their interests were much more directly involved than ours. And I think he was more influenced by that, and by the arguments for preventing this humanitarian disaster, than he was by any kind of broad strategic or philosophical commitment.”

Libya has become a cautionary case. The Obama Administration’s clearest foreign-policy victory has evolved into a civil war among militias. Power sensed the deepening disarray in early 2012, when the Libyan justice minister visited Washington and Americans urged him to prevent the torture of detainees in the Misrata area. “He said, ‘You want me to tell the Misratans what to do in their prisons?’ ” she recalled. “It wasn’t state failure. It was an absent state—a state failing to emerge.”

Conditions deteriorated further. Over the summer, the U.S. abandoned its embassy in Tripoli, an especially bitter move two years after Ambassador Christopher Stevens and three colleagues were killed in Benghazi. Obama has said that he “underestimated” the task of helping Libya fashion a new state after the Qaddafi era. He told Thomas Friedman, of the Times, “That’s a lesson that I now apply every time I ask the question ‘Should we intervene militarily? Do we have an answer the day after?’ ”

But Power is less forthcoming. We spoke for hours, and whenever I asked her about Libya’s disorder today she deflected the subject with talk of “challenges” and a frustrating insistence on returning to the past. “Whatever the challenges—and there were many in Libya today—I do think it is important to bear in mind what would have happened in Benghazi had the President not made the judgment that he did.” She went on, “I think you do have to ask yourself: Libya’s not doing well right now, no question. But it is quite likely that had Qaddafi done what he was inclined to do you would see exactly the dynamics that you see playing out today, combined with the slaughter of the state superimposed upon them.” On this subject, Power’s characterological direction of error may be the belief that a frank discussion of Libya’s lessons exposes her to deeper criticism, and could undermine support for future interventions. Libya was the first clear test of her toolbox, but she has stopped short of analyzing her record with the rigor that she once brought to the study of others.

Libya’s deterioration had a spillover effect. “For many in the government—including the President—Libya didn’t go so well,” the former senior White House aide told me. “If Libya had been a great success, that would’ve created more momentum on the Syria debate. And it wasn’t.”

Syria quickly became the Administration’s most vexing foreign-policy problem. The Arab Spring reached Syria in earnest in March, 2011, and by the middle of the year Power was arguing in internal White House meetings that arms should be provided to Syrian opposition figures. Dennis Ross told me, “She was drawing attention very early on to how Assad was turning this into a war.”

In August, 2012, American intelligence surmised that Assad’s military was mixing and moving chemical weapons. Clinton and others asked what it would take to vet and train moderate rebels. David Petraeus, who was then the C.I.A. director, proposed arming and training small groups of rebel forces at secret bases in Jordan, but Obama rejected the idea. In April, 2013, he reportedly changed his mind and created a secret program to train and arm the rebels. In August, 2013, a sarin-gas attack in Ghouta, an area outside Damascus, killed more than fourteen hundred Syrians, according to U.S. estimates. Obama raised the prospect of attacking the Assad regime’s facilities, and Power gave a forceful speech at the Center for American Progress in which she called for “a swift, limited, and proportionate strike so as to prevent and deter future use of chemical weapons.” She said the U.S. had exhausted all tools besides military force, and asked, “Does anybody really believe that deploying the same approaches we have tried for the last year will suddenly be effective?”

But the President ultimately decided against force, agreeing instead to a Russian-backed deal to remove Syria’s chemical weapons. The attacks on civilians continued. Power often struck a harsher tone in her statements than other Administration officials did. Last February, she called Syria “the most catastrophic humanitarian crisis any of us have seen in a generation,” adding, “The people of Syria are counting on us all.” But her jeremiads did not alter the dynamics of the war or America’s involvement.

Last summer, as ISIS made rapid gains, Power’s role in internal debates took a turn. She argued for a series of disruptive steps, beginning with the peaceful removal of Iraq’s Prime Minister, Nuri al-Maliki, because his presence made other Arab states—including Saudi Arabia, Qatar, and the United Arab Emirates—unwilling to coöperate. A former official described the sequence that Power promoted as follows: “Produce the transition of power in Iraq, produce the coalition, produce the train-and-equip, then put all these pieces together to push ISIS back on its heels.”

By late summer, ISIS was preparing to attack the Kurdish capital, Erbil, and thousands of members of Iraq’s Yazidi religious community had fled to the slopes of Mt. Sinjar. The U.S. launched air strikes to help them reach safety. Tom Malinowski, the Assistant Secretary of State for Democracy, Human Rights, and Labor, told me, “It was a very discrete situation. It was one ethnic group in one place that climbed one mountain, and we did one escape route without setting a single person on the ground. You didn’t have to worry about the exit strategy or the endgame.” Later, when ISIS made gains, Power pushed to resupply Shia Turkmen under assault in the town of Amerli, and to support Kurdish fighters in the Syrian city of Kobani.

When I asked Rhodes why Power’s arguments helped persuade the President to act in Libya but not in Syria, he said, “There was never a plan that would work. How could you know if you launched a humanitarian intervention that it wouldn’t make the situation worse on the ground? That there were targets to hit that weren’t going to leave an even greater imbalance behind? I think he never saw in Syria the type of option he had in Libya. That was the difference.”

Power acknowledges the trade-offs in geopolitics in a way that did not figure into her theories a decade ago. She told me, “You have to take into account the other collateral issues that you’re dealing with on the international stage. Our Ukraine standoff with Russia has bearing on our Syria political play; our effort to secure a nuclear deal that denies Iran a path to a nuclear weapon is a huge priority right now. That’s part of what’s on your mind as you’re thinking about particular tactical choices. So this composite calculus is what the President has to be doing all the time.”

To those who have worked to help remove Assad, the bombing campaign against ISIS has had the frustrating side effect of buoying his fortunes. On the third day of the air strikes, a Syrian official told a pro-government newspaper that now the U.S. was “fighting in the same trenches with the Syrian generals, in a war on terrorism.” Asked if she worried that the air strikes would fortify Assad, Power shifted the focus to emphasize that attacking ISIS will prevent mass atrocities. “ISIS, left at large, gobbling up villages, attracting foreign terrorist fighters, is good for no one. And tools short of military force were not stopping ISIs. Believe me: the tools in the toolbox were employed.”

But Ken Roth, of Human Rights Watch, was more explicit about the consequences of the “composite calculus.” “Striking in Syria is about depriving ISIS of a rear base,” he says. “So the U.S. doesn’t even describe it in humanitarian terms, quite deliberately, I think, because it doesn’t want to take on the mandate of stopping barrel bombs”—a horrific weapon that Assad has been using against Syrian civilians. He went on, “The Administration seems reluctant to use the two most likely avenues of pressure on Damascus—Moscow and Tehran—because that would divert attention from its higher priorities, stopping Russia’s quasi invasion of eastern Ukraine and securing a nuclear deal with Iran.”

For activists who have wanted Obama to do more to dislodge Assad, Power’s role has been a subject of intense interest. Mouaz Moustafa, an Arab-American activist in Washington, began meeting with Power when he was lobbying for U.S. intervention in Libya. Later, Moustafa, who is originally from Damascus, became the executive director of the Syrian Emergency Task Force, which pushes the U.S. to help the opposition in Syria. In one especially emotional meeting with Power, when he talked about the torture of civilians, both of them wept. “My impression of her was that she was the same Samantha that she was on Libya and would be able to move the President,” he said. “We just had to get her on board.”

But eventually Moustafa arrived at a different conclusion. “I came out of it thinking, No, she’s not quite the influential person that she was on Libya.” In July, Moustafa brought another activist, Emad ad-Din al-Rashid, a former assistant dean at the Islamic Law College in Damascus, to meet Power at the Washington outpost of her U.N. office. “He says to her, ‘We have read your book “ ‘A Problem from Hell,’ ” and this seems to be the problem from hell now.’ ” He said she was struck by those comments, “because this is a guy who is not even an American citizen and he knew that about her.” Rashid urged her to “write the book about a new problem from hell.” She replied, “Well, first we need to figure out how to solve it.”

Moustafa told me, “Because I care about her, I do not want her to become those she criticized in her book.” He added, “I do not want the next book that Samantha writes to be ‘The Education of Samantha Power,’ about how ‘it’s more complicated than I thought when I wrote my first book.’ No, I want her to be just as idealistic as when she wrote her first book.”

Because she once wrote admiringly about Clinton Administration officials who resigned over inaction in Bosnia, her critics say that she should resign over Syria. In May, Jennifer Rubin, a conservative columnist and blogger at the Washington Post, accused Power of “simple careerism,” writing, “Staying put doesn’t make one noble; it makes one an enabler of the policies one finds despicable.”

I asked Power if she has ever thought of stepping down. “My basic view is that there is an awful lot of good that one can do in these jobs, and you have to look at the composite,” she said. “I don’t think you can care as much about civilian protection, atrocity prevention, accountability, as I do, or as President Obama does, and be satisfied with Syria. By the same token, I have the privilege every day of being able to try to steer the ship of U.N. peacekeeping, to open the gates to civilians fleeing mass violence in South Sudan, or try to push for a peacekeeping force to be deployed to the Central African Republic, or, on Ebola, try to counteract some of the fear that might impede some of the response. I’m conscious of the risk of self-rationalization and self-perpetuation and so forth. But this is not a close call for me.”

Leon Wieseltier, the former literary editor of The New Republic, is one of Sunstein and Power’s closest friends. In a toast at their wedding, he called Power “one of the keepers of idealism in America,” who “remains almost giddily unreconstructed in her imagination of justice.” He is also one of Obama’s most acerbic critics. When I visited Wieseltier at his office, in Washington, he excoriated the President for an hour, calling him a “coldhearted realist” who deploys “high moral language followed by inaction, or grudging action, or ineffective action,” thus emboldening Vladimir Putin and Assad.

Wieseltier does not speak directly with Power about Obama, because she knows his views and he does not expect her to criticize her boss. Instead, he needles her in print. In May, 2013, he wrote, “Must the learning curve of Presidents always cost so many corpses? Has anyone at the White House read Samantha Power’s book?”

He sees Power’s role in the Administration as “the in-house conscience,” he said. “She lifts the President up and reminds him of moral principles and ethical duties, and adds a sense of historical grandeur, and won’t let him forget the Holocaust and Bosnia and Rwanda and the rest. And I imagine that for Obama it feels so good and so toasty—aren’t we really sterling people, and now let’s not do anything. This is not saying anything bad about Samantha. Her sincerity and her devotion to principle are beyond question. But she plays a certain role in Obama’s ecosystem.”

When I put that idea to Power, she said, “I can be a pain in the ass, and that’s what he wants. That’s what’s so amazing. There are plenty of people out there who could check the conscience box.” She went on, “There are milder personalities that could create the illusion of inclusion, and spare you the headache of argument and counter-argument, and President Obama did not choose that milder version.”

On November 7th, three days after Republicans triumphed in the midterm elections, gaining control of the Senate, the President summoned his Cabinet for a meeting. In an armored Suburban a few hours afterward, Power pulled out a white notecard distributed at the meeting and inscribed with a quote from Obama: “We are entering the fourth quarter, and really important things happen in the fourth quarter.” Power, whose reverence for Obama is undimmed, glanced at it, showed it to me, and then tucked it back among her things.

The outlines of her legacy were becoming clear: she had influenced a range of issues outside the center ring, including Ebola and the Central African Republic, but on the most essential crises of her time—Syria and Iraq—she had been forced to accept the limits of her ability to shape events. Power rejects the facile narrative that presents itself—the education, the chastening. “The way that kind of story is told is ‘She wrote the book, she was critical because she didn’t really understand how hard it was,’ ” she said. “And then the assumption is Eliza Doolittle learned how hard it is, and then that makes her less critical, or more accepting of crummy outcomes.” She argued, “You learn in government what the obstacles are. But that’s not so you can go take a nap. It’s so you can figure out how to scale them or work around them. Does one get a better sense about context and about impediments and about trade-offs in government? Absolutely. But those are not alibis—those are problems to be solved.”

Power and Obama entered the Administration farther apart than their pedigrees and their friendship might have suggested: she advocated intervention and American exceptionalism; he spoke of America as the most powerful leader in the world, but recoiled from the adventurism of the Bush wars and the presumption of enduring American primacy, focussing instead on the need to rebuild the country at home. After nearly six years, Power still believes that America retains the capacity for brute or moral force to shape the course of global events—to bend the curve—but Obama, by his own account, does not. To some degree, there has always been a contradiction between the Administration’s determination to retrench from the costly adventures in Iraq and Afghanistan and the expectation of restoring American credibility through moral leadership and actions.

From the outside, it was tempting to see Power as the brooding dissident inside, and many of her associates assume that she is troubled by the Administration’s inaction on Syria. (In reality, few of them know; Power rarely discusses her work with them now.) If, in fact, she was anguished, and she remained inside, she would become vulnerable to the charge of hypocrisy. Power’s hope is to be viewed as a happy warrior: “I’ll be that person grabbing the base of the couch, and they’ll be pulling my feet out of the office. I’m very, very happy where I am.”

And so Power must defend the Obama Administration both against the criticism that it is doing too little in Syria and against the criticism that it is doing too much. When I mentioned the fears of a quagmire, she showed a flash of irritation. “Many of the same people who are very, very concerned about a slippery slope are the very same who are horrified by the enslavement of Yazidi women and children, and who look at the killing of Jim Foley as one of the most iconically heartbreaking events of our lifetime, and who recognize that, when ISIS says that it is intent on doing something, unless it is stopped, it is likely to project force in a manner that propels it forward.” She insisted, “But I definitely do not see a scenario where we are heading down some slippery slope and ending back in the Iraq War, or anything of that nature.”

Power wrote of Sergio Vieira de Mello, “He started out as a humanitarian,” but, after years of contending with crises around the world, “he had become a diplomat and politician, comfortable weighing lesser evils.” She called him a “Machiavellian idealist.” She told me, “As time wears on, I find myself gravitating more and more to the G.S.D. people”—the “get shit done” people, a term favored by Susan Rice. “We’re racing against the clock here to get as much done as we can. So when you run across people who know how to be bureaucratic samurais, or are especially persuasive in their diplomacy internationally, spend more time on those relationships, and on brainstorming with those individuals, to achieve a common purpose. Principles and positions only take you so far.” ♦